The present invention relates generally to detecting devices. More particularly, the invention relates to a product detecting device useful in a system for the manufacture of processed board product, such as oriented strand board (OSB), or the like, to determine the existence of a system malfunction, whereby operation of the system can be terminated and the malfunction corrected.
A desirable alternative to natural solid wood, particularly for the properties of strength, durability, stability and finish is multi-layered oriented strand board, hereinafter referred to as OSB. Such material consists of several layers of thin wood strands, which are wood particles having a length greater than their width, arranged in cross-oriented layers. In practice, the strands are produced by slicing larger pieces of wood in a manner that the fibers in each strand are aligned substantially parallel to the strand length. The strands, to which a binder, such as urea or a resinous material, has been applied, are disposed on fine mesh metal screens in layers to form a relatively loose mat. The strands in each layer are positioned relative to each other with the long dimension of each in substantial parallel relation. Strands in adjacent layers, however, are disposed in substantial perpendicular or cross-oriented relation. The mat is compressed in a pressing device to the extent required to produce the desired board thickness. The resultant product is, thus, a compacted sheet or panel of board comprised of multi-layered, cross-oriented wood strands.
OSB board is typically produced on a production line in which the mats of layered wood strands mounted on screens are carried by appropriate transfer apparatus to a loading station at which the screens are placed each into a separate compartment of a multi-level cage from whence each can be transferred to a multi-platen press. In present-day production systems as many as fifteen or more mats may be compressed simultaneously in the press and, thereafter, delivered to an unloading station where the compacted product is removed from the respective transfer screens for transport to storage or to another operating station and the transfer screen recycled via a conveyor arrangement within the production system.
A problem frequently encountered in production systems of the described type is that a sheet, following compacting in the press, may not be completely delivered to the unloading station. This can result from a compacted sheet becoming lodged within the press whereupon the screen is moved into the unloading station leaving the sheet product behind in the press. Alternatively, the compacted sheet may become displaced on its transfer screen and only partly moved into the unloading station. In either case, the errant compacted sheet can result in damage to the equipment and thereby the cause of undesirable downtime of the system.
Accordingly, it is to the solution of such problems to which the present invention is directed.